1. Field of the Invention
The present invention relates to a control device for an automatic transmission for a vehicle, in particular, to the control device for the automatic transmission having a shift lock system which can securely avoid plural improper selective operations of a select lever by a single lock member.
2. Discussion of the Related Art
A conventional control device for an automatic transmission has a shift lock system which permits selective operations of a select lever from a parking position to other range positions only when a brake pedal is actuated for example, at starting time of an automobile. The shift lock system preferably avoids a selective operation from a neutral position to a reverse position while driving of the automobile.
The shift lock system in the transmission control device usually has each lock member used in each case to restrict the selective operations by putting each lock member into operation at each predetermined operating condition in order to restrict the selective operations in the above two cases.
However, operating two kinds of lock members at predetermined operation conditions requires many components to be used and leads to a complex shift lock system. Furthermore, assembly of the shift lock system needs considerable hours and costs.
JP-A-8334167 discloses the control device for the automatic transmission having the shift lock system in which a single lock member avoids both selective operations from a parking position to other range positions and a selective operation from a neutral position to a reverse position at predetermined operating conditions.
The control device, as schematically shown in FIG. 22, includes a select lever 205 rotatably supported on a housing 201 and a gate 202 as an opening having a step-like configuration, the latter of which contains range positions for an automatic mode including a series of a parking position, a parking release position, a reverse position, a reverse preparing position and a neutral position. This gate type transmission control system performing the selective operations of the select lever 205 by engaging the select lever 205 with any of the range positions of the gate 202, is provided with an engaging projection 206 on one side of the select lever 205 and a single lock member 210 rotatably supported on the housing 201 through a rotary shaft 209. The lock member 210 rotates around the rotary shaft 209 with the aid of an electric solenoid 212 to obtain either a working position (shown in solid lines) for avoiding the selective operation from the parking position to the parking release position and the selective operation from the neutral position to the reverse preparing position by contacting a head end surface of the engaging projection 206 or a nonworking position (shown in imaginary lines) for avoiding contact therewith at predetermined operational conditions.
According to the above mentioned transmission control device disclosed in JP-A-8334167, both the selective operations of the select lever 205 from the parking position to other range positions and the selective operation from the neutral position to the reverse position are effectively restricted by rotating the lock member 210 to have the working position. The above selective operations are permitted by rotating the lock member 210 to have the nonworking position.
The lock member 210, however, has a substantial length and a large space for the shift lock system, because the single lock member 210 supported on the rotary shaft 209 has to be operated for avoiding both the selective operations from the parking position to the parking release position and from the neutral position to the reverse preparing position.
In the improper selective operations of the select lever 205 from the parking position to the parking release position and from the neutral position to the reverse preparing position, some stress from the lock member 210 to the engaging projection 206 acts on the contacting region of the lock member 210 in a direction substantially perpendicular to the extended direction of the lock member 210. Significant large stress hence acts on both the rotary shaft 209 for supporting the lock members 210 and the supporting region thereof in the housing 201. This large stress leads to frictional wear of the supporting region and consequently a short time durability of the transmission control device. Therefore, a corrective measure, for example, supporting the rotary shaft 209 on both sides of the housing 201, may be required.
Supporting the rotary shaft 209 on both sides of the housing 201 increases the amount of space occupied by the shift lock system and the size of the transmission control device itself, thus, the weight of the transmission control device and the cost of manufacture as well.
It is therefore an object of the present invention to provide a control device for an automatic transmission having a shift lock system which securely prohibits plural improper selective operations of a select lever by a lock member.
It is other object of the present invention to provide the control device for the automatic transmission with a durable shift lock system.
It is further object of the present invention to provide the control device for the automatic transmission having the shift lock system of very small size, and which is very light in weight and a low cost to manufacture.
It is another object of the present invention to provide the control device for the automatic transmission having the shift lock system which consumes only a little amount of electric power.
The above objects are achieved by the automatic transmission control device for the vehicle comprising: a housing for including the transmission control device; a first rotary shaft supported on the housing and extended in a substantially widthwise direction of a vehicle body; a lock plate with a guide opening containing range positions for an automatic transition mode including a series of a parking position, a reverse position, a neutral position and a driving position; a select lever supported on the first rotary shaft and being rotatable for selecting one of the range positions; a guide pin supported on the select lever, an end of the guide pin for defining a selective operation of the select lever accepted in the guide opening so as to engage with any of the range positions; and a specific shift lock system for prohibiting the selective operation of the select lever.
The shift lock system in the transmission control device comprises a lock pin extending substantially in parallel with the first rotary shaft, the lock pin being movable in a lengthwise direction of the vehicle body with response to a rotation of the select lever; a second rotary shaft supported on the housing and extended substantially in parallel with the first rotary shaft; and a lock member having a lock part supported on the second rotary shaft so as to rotate around the second rotary shaft to have one of a lock position and an unlock position, the lock position for prohibiting the selective operation of the select lever by bringing the lock part into a contact with a periphery of the lock pin.
The above object are also achieved by the automatic transmission control device for the vehicle comprising: a housing for including the control device; a first rotary shaft supported on the housing and extended in a substantially widthwise direction of an vehicle body; a third rotary shaft extended substantially perpendicularly to a longitudinal direction of the first rotary shaft; a select lever being rotatable around both the first rotary shaft and the third rotary shaft for selecting one of range positions for an automatic transmission mode; a gate provided in the housing containing the range positions including a series of a parking position, a reverse position, a neutral position and a driving position for defining the selective operation of the select lever; and the above specific shift lock system for prohibiting the selective operation of the select lever.
The shift lock system according to the present invention is arranged such that the lock part of the lock member enters into a movement track of the lock pin and locks the lock pin by contacting the periphery when an improper selective operation of the select lever is attempted to be carry out, and such that the lock part moves away from the movement track of the lock pin and releases the lock pin by avoiding the contact when an selective operation is acceptable. According to the present invention, the improper selective operations are securely prohibited by the single lock member. Furthermore, rotating of the lock member on the second rotary shaft provides a small lock member, a compact shift lock system and a transmission control system of very small size which is very light in weight and inexpensive to manufacture.
In the improper selective operations of the select lever, some stress from the periphery of the lock pin to the engaging region of the lock part acts on both the rotary shaft part and a supporting region thereof in a direction substantially perpendicular to the longitudinal direction of the second rotary shaft. As a result, unbalanced stress on the second rotary shaft and the supporting region are significantly reduced. Therefore, the requirement to the stiffness and wear resistance of these parts decreases, and simple structures of the parts can be obtained.
According to the present invention, it is possible to prohibit plural selective operations, such as the selective operation from the parking position to the reverse position, from the neutral position to the reverse position, and from the reverse position to the other positions, by changing a shape of the lock part of the lock member.
Furthermore, it is possible to prohibit an improper selective operation in an advantageous condition by placing the lock pin on a lock pin bracket which moves around the first rotary shaft together with the select lever.
According to the present invention, the driving means can be easily structured by an electric solenoid for rotating the lock member from the lock position to the unlock position. The solenoid is preferably arranged to operate only when a brake pedal is actuated. In this manner, it is possible to decrease the amount of electric power consumed by the solenoid.
Further aspects of the present invention will be clearly understood from the claims, the drawings and the written descriptions.